The Codex Astartes describes the organisation, tactical operation
and countless other aspects of Space Marine doctrine. Subjects as diverse
as religious instruction and strategic supply are all covered in great
detail within its thousands of holopages. Over the following pages we
will look at the origins of this ancient tome and also how it states
a Space Marine Chapter should be organised.

The Horus Heresy

Of
the original twenty Primarchs, Horus was the greatest and most beloved
of the Emperor and so was appointed his Warmaster. He was placed in
charge of the entire northeastern battlefront of the Great Crusade and
only Lion El Jonson and Leman Russ approached his tally of victories.
Little did the Emperor know that Horus really served a darker master.
The gods of Chaos, malevolent beings from the warp, had corrupted Horus
and his armies, turning them from the Emperors light. Their plan
was a foul and devious one.

They would allow the Emperor to possess the galaxy for a fleeting moment
only. He would be encouraged to stretch his empire further and further
from Terra, until his forces were scattered thinly along the galactic
fringe. Then the dark gods would strike and crush the Emperor with one
swift blow. When rebellion erupted, Horus led more than half of the
Space Marine Legions into the bloodiest civil war ever to engulf the
galaxy and laid siege to the Emperors Palace. It would take many
pages to describe the battle for Earth, suffice to say the war ended
when the Emperor teleported onto Horuss battle barge and slew
the Warmaster in single combat. The titanic struggle saw the Emperor
mortally wounded and from that moment on he ceased to live in the conventional
sense. Rogal Dorn, Primarch of the Imperial Fists discovered the Emperors
dying body and carried it back to Earth where he was interred in the
life preserving mechanism of the Golden Throne. And for ten thousand
years since that day, the Emperor has ruled immobile and immortal from
the throne of Earth.

Though the Horus Heresy was at an end, the galaxy was in turmoil once
more. The armies of the Imperium were destroyed or scattered and worst
of all, the Emperor could no longer walk amongst his warriors. The leadership
and guidance he had given humanity for thousands of years was suddenly
absent. To lead mankind, a council was formed of the twelve most powerful
individuals in the Imperium. They became known as the High Lords of
Terra, and their role was to rule the Imperium on behalf of the Divine
Emperor.

The Codex Astartes

To die without purpose is not a service to the
Emperor. It is a heresy to waste lives entrusted to you as an
Imperial officer. There is nothing shameful or disloyal in righteous
retreat. But in withdrawing from the enemys presence, allow
him no succour. That which cannot be saved must be destroyed.
Leave no weapons, armour, transport, food or water in your passing.
Scorch the earth at his feet, and leave him desert and desolation
as his victory gifts.

Codex Astartes

The newly created High Lords established the organisation of the Imperium
that remains familiar to this day. The first High Lords laid down the
structure by which the Adeptus Terra operates, and described the feudal
responsibilities and duties of planetary lords. One of their most important
accomplishments was the reorganisation of the Imperiums armed
forces. This task was undertaken almost singlehandedly by the Primarch
of the Ultramarine Legion of Space Marines, Roboute Guilliman, who quickly
and efficiently codified the structure of the Imperial Guard, the Fleet
and the Space Marines. Of all his works the most influential is the
Codex Astartes, the great prescriptive tome that lays down the basic
organisational and tactical rules for Space Marines. The Horus Heresy
had revealed weaknesses in the geneseed of several Space Marine Legions
which had been exaggerated by the accelerated zygote harvesting techniques
needed to keep the huge Space Marine Legions up to strength. The powers
of Chaos exploited this growing physical and mental corruption to turn
Horuss troops against the Emperor. The prime objective of the
new Codex Astartes was to recognise and expunge these weaknesses.

The Codex decreed that Space Marines would be created and trained over
a controlled period of time. The genetic banks used to cultivate implants
would be carefully monitored and cultivated organs would be subject
to the most stringent tests of purity. Young initiates would undergo
rigorous trials of physical and psychological suitability before they
were accepted, and only those of the highest calibre would be chosen.

THE DARK FOUNDING

Not all the foundings of Space Marine Chapters
are recorded in exact detail. However, the Adeptus Terra maintains
a single bank of original gene-seed from every single Chapter
ever created since the Horus Heresy. There is one notable exception:
the Thirteenth Founding, also known as the Dark Founding. No-one
knows how many Chapters were created by the Dark Founding or what
became of them. Perhaps the secret lies in some deep vault in
the record office of the Adeptus Terra. Maybe the Space Marines
of the Dark Founding are still out there somewhere, waiting to
return to the world that created them.

On Earth the Adeptus Terra created genetic repositories to produce
and store Space Marine gene-seed. These banks were used to provide all
new gene-seed for Space Marines, and, to prevent cross-contamination,
the genetic material of each of the old Legions was isolated. Henceforth
the new Space Marine Chapters would receive gene-seed only from their
own genetic stock.

The gene-seed of the Traitor Legions was placed under a time-locked
stasis seal, although at the time many believed these dangerous gene
stocks should be destroyed. By taking direct control of the genetic
stocks, the Adepts on Earth could ultimately control the Space Marines.
Now they alone had the power to destroy or create Space Marine armies
at will.

The Second Founding of the Space Marines was decreed seven years after
the death of Horus. The existing Space Marine Legions were broken up
and refounded as smaller, more flexible formations. Where the old Legions
were unlimited in size, the new formations were fixed at approximately
one thousand fighting warriors. This corresponded to the existing unit
called the Chapter, and in future the Chapter was recognised as the
standard autonomous Space Marine formation. No longer would one man
have power over a force as powerful as a Space Marine Legion.

The
existing Space Marine Legions were divided into new Chapters, one Chapter
keeping the name and colours of the original Legion, while the remaining
Chapters would take new titles and colours. Most of the old Legions
divided into fewer than five Chapters, (the Space Wolves divided into
only two) but the Ultramarines were divided many times. The exact number
of new Chapters created from the Ultramarines is uncertain: the number
listed by the oldest known copy of the Codex Astartes (the so-called
Apocrypha of Skaros) gives the total as twenty three, but does not name
them.

As a result of the Second Founding the Ultramarines geneseed
became the favoured gene-seed of most subsequent foundings. The new
Chapters created from the Ultramarines are often referred to as the
Primogenitors, or first born. All the Primogenitor Chapters
venerate Roboute Guilliman as their founding father and patron.

The Codex Astartes further defines the tactical roles, equipment specifications
and uniform identification markings of the Space Marines. These guidelines
have evolved over the centuries, and the Codex Astartes of the forty
first millennium is a highly developed treatise combining the wisdom
of hundreds of military thinkers throughout history. Some of its contents
seem petty and restrictive, hardly worthy of the great mind of the Primarch.
Others describe actual battles together with comments on the tactics
employed and the decisions of the commanders of the day. As such the
Codex Astartes is revered as a holy text, and many Chapters regard its
recommendations as sanctified by the Emperor himself.

The Codex Chapters

The Chapters that rigidly follow the recommendations of the Codex Astartes
are sometimes referred to as Codex Chapters. These Space Marines adhere
to the Codex as the model for their organisation, identification markings
and tactical doctrine. Of all the Codex Chapters the most famous is
the Ultramarines, the Chapter of Roboute Guilliman himself, and many
of the other Codex Chapters are descended from their genetic line.

THE CURSED FOUNDING

The Twenty First Founding was the largest since
the Second Founding. It took place sometime immediately before
the Age of Apostasy, a time of civil war which divided and almost
destroyed the Imperium. The new Chapters were dogged by bad luck
right from the start. Several disappeared mysteriously whilst
in action or in warp space. Every surviving Chapter of the founding
is affected by spontaneous genetic mutation of its gene-seed.
As a result the Chapters have gradually dwindled in size as their
inability to raise and induct recruits means that battle casualties
cannot be replaced. Worse still, some Chapters have developed
genetic idiosyncrasies, mutations which strain the tolerance of
the Inquisition and threaten the Chapters' survival. Few Chapters
have suffered as ignominious an end as the Flame Falcons whose
spontaneous and extreme physical corruption turned them into a
race no longer human or sane. The Chapter was declared Excommunicate
and driven from its home world of Lethe by the Grey Knights.

Most Chapters, however, do not stick so rigidly to the Codex patterns
laid down either for organisation, tactical roles or other processes.
Many Chapters are largely organised according to the Codex but are further
shaped by their home world and the personality of their Primarch. The
Blood Angels and Dark Angels are prime examples of this. A small number
of Chapters are vastly different from the Codex, and owe nothing at
all to it. The most famous of these wild Chapters are the
Space Wolves, whose strongwilled Primarch, Leman Russ, moulded his Chapter
very much in his own image irrespective of other influences.

The Adeptus Terra has never felt it necessary to enforce the Codex
absolutely. Indeed it is doubtful whether it could. However, with subsequent
foundings they have always favoured the Ultramarines' gene-seed and
created new Codex Chapters from their line. With the passage of time,
some of these Chapters have subsequently strayed from the strict letter
of the Codex, introducing new variations but remaining broadly faithful
to the principles laid down by Roboute Guilliman many thousands of years
before.

Subsequent Foundings

The history of the Imperium since the Heresy is not a continuous story.
There have been periods of rebellion and anarchy, times when the balance
of power has suddenly changed and history has been quite literally rewritten.
Many of the subsequent foundings of Space Marines belong to these troubled
times, making it almost impossible to be certain when some Chapters
were created or even how many Chapters have been created at all. It
is believed that there are approximately a thousand in existence today,
scattered throughout the galaxy. Of these more than half are descended
from the Ultramarines, either directly or through one of the Primogenitor
Chapters of the Second Founding.

The Second Founding

It is not certain how many new Chapters were created by the Second
Founding. Many Imperial records were lost during the Age of Apostasy,
a troubled time that lies across the history of the Imperium like an
impenetrable veil. In all likelihood some of the Chapters created during
the Second Founding have since been destroyed leaving no record of their
deeds. Others have been lost in more recent times and their names are
now all that remain of them.

Chapter Organisation

Following the Horus Heresy the Space Marine Legions were divided into
Chapters consisting of roughly a thousand warriors. A large section
of the Codex Astartes is dedicated to structuring the organisation of
these Chapters. A Chapter consists of ten Companies each numbering 100
Space Marines. A Company consists of ten squads of ten men including
a Sergeant. In addition to this basic fighting unit, each company has
its own Captain, Standard Bearer, Chaplain and Apothecary.

Every Company with the exception of the Scout Company maintains Rhino
transports for their squads and officers. The 1st Company is also equipped
with Land Raiders to carry Terminator squads. It is customary for Dreadnoughts
to remain with their Company as their fearsome presence bolsters the
Companys fighting strength.

A Chapter also includes a number of officers and specialists
who stand aside from the Company organisation. These individuals
are known as the Headquarters staff and they may be assigned to
fight with a Company in battle. Included amongst them are psychic
Librarians from the Chapters Librarius and Techmarines,
together with their Servitors. Although the Codex describes a
number of ranks and responsibilities within the Headquarters staff,
only a very few of these officers actually accompany the Chapter
to war. Many are noncombatants of advanced years whose roles are
to recruit and train new members or administrate the Chapter.
Some ranks described by the Codex include the Chapters Ancient
(or Standard Bearer), the Masters Secretarius, the Lord
of the Household, the Chapters Armourer, the Commander of
the Fleet, Victuallers, the Commander of the Arsenal, Commander
of Recruits and Commander of the Watch.

The 2nd, 3rd, 4th and 5th are Battle Companies,
each consisting of six squads of Tactical Space Marines, two of
Assault, and two of Devastators. These four Battle Companies form
the main battle lines and generally bear the brunt of the fighting.
The Assault squads of the Battle Company may be deployed as Bike
squadrons or Land Speeder crews.

Of the ten Companies comprising a Chapter, the
1st Company consists of veteran troops and is invariably the most
powerful. The 1st Company is the only one trained to use the treasured
suits of Terminator armour.

The Chapter’s 10th Company is its Scout Company
consisting of a number of Scout squads. Scouts are youths who
have been recruited and partially transformed into Space Marines.
Until their physical transformation and training is complete they
fight as Scouts. There is no formal size for a Scout Company as
the rate of recruitment is not fixed.

Companies 6 and 7 are Tactical Companies, each
consisting of ten Tactical squads. These are intended to act as
a reserve and may be used to reinforce the main battle line, launch
diversionary attacks or stem enemy flanking moves. The 6th Company
is also trained to fight on bikes and the entire Company may be
deployed as bike squadrons. Similarly the 7th Company squads are
trained to fight from Land Speeders enabling the Company to fight
as a light vehicle reserve formation.

The 8th Company is an Assault Company consisting
of ten Assault squads. This is the most mobile Company and
is often used wherever a strong hand-to-hand fighting force
is needed.

The 9th Company is a Devastator Company,
consisting of ten Devastator squads armed with heavy weapons.
They anchor defence points and provide long range fire support.

Squad Organisation

According to the Codex Astartes, Space Marines are
organised into three different types of squad: Tactical,
Assault and Devastator. Each of these squads has a
unique battlefield role and are designed to operate
together to provide mutual support and maximum
flexibility. In addition to these three squads the Ist
(Veteran) Company can be formed into Terminator or
Veteran squads while the Scouts are always fielded as
Scout squads.

Tactical squads are the most commonly found squad in a Chapter. A Tactical
squad is led by a Sergeant and includes nine other Space Marines. Of these,
seven Space Marines are armed with boltguns, whilst the remaining two can be
armed with boltguns or, alternatively, one may carry a heavy weapon and the
other may carry a special weapon. This combination is the most tactically flexible
and offers a good mixture of capabilities within the squad.

Assault squads are specialists at fighting in hand-tohand combat. Each
squad consists of a Sergeant and nine Space Marines equipped with jump packs
and armed with a close combat weapon in each hand. Common armament consists
of a bolt pistol and chainsword. Optionally, two of the Space Marines may carry
plasma pistols. This combination is ideal for fastattacking, close-quarter fighting
assault troops.

Devastator squads consist of a Sergeant and nine Space Marines. Up to
four Space Marines may be armed with heavy weapons, whilst the remainder will
carry boltguns. This is the most heavily armed type of Space Marine squad of
all and they are deployed wherever extra fire-support is needed, especially
when the Chapter faces enemy tanks or fortified positions.

Terminator squads wear the uniquely powerful Terminator armour. This
is massive in construction virtually turning a Space Marine into a one-man tank.
Every Chapter has a limited number of Terminator armoured suits, and each is
an ancient artefact crafted many thousands of years ago. Terminators are less
mobile than other Space Marines and are primarily used in boarding actions or
at extreme close quarters when heavy firepower cannot be brought to bear.

Veteran squads are organised exactly like the Tactical squads of the
Battle Companies. The Sergeant and the nine Space Marines are all Veterans.
These squads are rarely deployed en masse but are sometimes used to strengthen
an attack or provide the Chapter with flexible, hard-hitting reserves.

Scout squads consist of a Space Marine Sergeant and four Scouts. The
role of the Sergeant is to train the Scouts and lead them in battle. Only Sergeants
of considerable experience and status are designated for this role.

All Space Marine squads with the exception of the
Scouts are nominally of ten troopers, but can be
divided into two separate battle squads in combat. This
gives each unit a further degree of flexibility in action.